[gdal-dev] Feature Request: Round overview levels

[AlexUSACE]

Hi devs-

I'd like to be able to round overviews via a flag in gdaladdo. This has
several benefits, but the primary one is the (zipped) file size.

For interpolated values like overviews, rounding doesn't actually hurt the
integrity of the data. Many of our terrain grids are from older surveying
data, and are at *best* accurate to the nearest foot. 8 digits of precision
for the overviews is just noise. We started rounding our data manually, and
we're seeing a 20%+ size reduction in many datasets. 

I dug through the source, and it seems like it would take relatively few
changes for someone who knew what they were doing. Frankly I'm not familiar
enough with the source to guarantee I wouldn't generate some sneaky bugs if
I did it myself.

Would anyone else use this feature? Of course we can go back and manually
edit the data after gdaladdo does its magic, but that requires a second pass
through our 5+ GB tiff files. Not a pretty solution. If anyone else has
faced a similar problem and found a decent solution, I'd love to hear it. At
the moment all of our development is in .Net. We're doing most of our GDAL
calls through the prebuilt exe's, though some of our code uses the C# swig
bindings.

Thanks,
Alex



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